--- /dev/null
+/*
+ * devtmpfs - kernel-maintained tmpfs-based /dev
+ *
+ * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
+ *
+ * During bootup, before any driver core device is registered,
+ * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
+ * device which requests a device node, will add a node in this
+ * filesystem. The node is named after the the name of the device,
+ * or the susbsytem can provide a custom name. All devices are
+ * owned by root and have a mode of 0600.
+ */
+
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include <linux/shmem_fs.h>
+#include <linux/cred.h>
+#include <linux/init_task.h>
+
+static struct vfsmount *dev_mnt;
+
+#if defined CONFIG_DEVTMPFS_MOUNT
+static int dev_mount = 1;
+#else
+static int dev_mount;
+#endif
+
+static int __init mount_param(char *str)
+{
+ dev_mount = simple_strtoul(str, NULL, 0);
+ return 1;
+}
+__setup("devtmpfs.mount=", mount_param);
+
+static int dev_get_sb(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *data, struct vfsmount *mnt)
+{
+ return get_sb_single(fs_type, flags, data, shmem_fill_super, mnt);
+}
+
+static struct file_system_type dev_fs_type = {
+ .name = "devtmpfs",
+ .get_sb = dev_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+#ifdef CONFIG_BLOCK
+static inline int is_blockdev(struct device *dev)
+{
+ return dev->class == &block_class;
+}
+#else
+static inline int is_blockdev(struct device *dev) { return 0; }
+#endif
+
+static int dev_mkdir(const char *name, mode_t mode)
+{
+ struct nameidata nd;
+ struct dentry *dentry;
+ int err;
+
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ name, LOOKUP_PARENT, &nd);
+ if (err)
+ return err;
+
+ dentry = lookup_create(&nd, 1);
+ if (!IS_ERR(dentry)) {
+ err = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode);
+ dput(dentry);
+ } else {
+ err = PTR_ERR(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+
+ path_put(&nd.path);
+ return err;
+}
+
+static int create_path(const char *nodepath)
+{
+ char *path;
+ struct nameidata nd;
+ int err = 0;
+
+ path = kstrdup(nodepath, GFP_KERNEL);
+ if (!path)
+ return -ENOMEM;
+
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ path, LOOKUP_PARENT, &nd);
+ if (err == 0) {
+ struct dentry *dentry;
+
+ /* create directory right away */
+ dentry = lookup_create(&nd, 1);
+ if (!IS_ERR(dentry)) {
+ err = vfs_mkdir(nd.path.dentry->d_inode,
+ dentry, 0755);
+ dput(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+
+ path_put(&nd.path);
+ } else if (err == -ENOENT) {
+ char *s;
+
+ /* parent directories do not exist, create them */
+ s = path;
+ while (1) {
+ s = strchr(s, '/');
+ if (!s)
+ break;
+ s[0] = '\0';
+ err = dev_mkdir(path, 0755);
+ if (err && err != -EEXIST)
+ break;
+ s[0] = '/';
+ s++;
+ }
+ }
+
+ kfree(path);
+ return err;
+}
+
+int devtmpfs_create_node(struct device *dev)
+{
+ const char *tmp = NULL;
+ const char *nodename;
+ const struct cred *curr_cred;
+ mode_t mode;
+ struct nameidata nd;
+ struct dentry *dentry;
+ int err;
+
+ if (!dev_mnt)
+ return 0;
+
+ nodename = device_get_nodename(dev, &tmp);
+ if (!nodename)
+ return -ENOMEM;
+
+ if (is_blockdev(dev))
+ mode = S_IFBLK|0600;
+ else
+ mode = S_IFCHR|0600;
+
+ curr_cred = override_creds(&init_cred);
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ nodename, LOOKUP_PARENT, &nd);
+ if (err == -ENOENT) {
+ /* create missing parent directories */
+ create_path(nodename);
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ nodename, LOOKUP_PARENT, &nd);
+ if (err)
+ goto out;
+ }
+
+ dentry = lookup_create(&nd, 0);
+ if (!IS_ERR(dentry)) {
+ err = vfs_mknod(nd.path.dentry->d_inode,
+ dentry, mode, dev->devt);
+ /* mark as kernel created inode */
+ if (!err)
+ dentry->d_inode->i_private = &dev_mnt;
+ dput(dentry);
+ } else {
+ err = PTR_ERR(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+
+ path_put(&nd.path);
+out:
+ kfree(tmp);
+ revert_creds(curr_cred);
+ return err;
+}
+
+static int dev_rmdir(const char *name)
+{
+ struct nameidata nd;
+ struct dentry *dentry;
+ int err;
+
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ name, LOOKUP_PARENT, &nd);
+ if (err)
+ return err;
+
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
+ if (!IS_ERR(dentry)) {
+ if (dentry->d_inode)
+ err = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+ else
+ err = -ENOENT;
+ dput(dentry);
+ } else {
+ err = PTR_ERR(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+
+ path_put(&nd.path);
+ return err;
+}
+
+static int delete_path(const char *nodepath)
+{
+ const char *path;
+ int err = 0;
+
+ path = kstrdup(nodepath, GFP_KERNEL);
+ if (!path)
+ return -ENOMEM;
+
+ while (1) {
+ char *base;
+
+ base = strrchr(path, '/');
+ if (!base)
+ break;
+ base[0] = '\0';
+ err = dev_rmdir(path);
+ if (err)
+ break;
+ }
+
+ kfree(path);
+ return err;
+}
+
+static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
+{
+ /* did we create it */
+ if (inode->i_private != &dev_mnt)
+ return 0;
+
+ /* does the dev_t match */
+ if (is_blockdev(dev)) {
+ if (!S_ISBLK(stat->mode))
+ return 0;
+ } else {
+ if (!S_ISCHR(stat->mode))
+ return 0;
+ }
+ if (stat->rdev != dev->devt)
+ return 0;
+
+ /* ours */
+ return 1;
+}
+
+int devtmpfs_delete_node(struct device *dev)
+{
+ const char *tmp = NULL;
+ const char *nodename;
+ const struct cred *curr_cred;
+ struct nameidata nd;
+ struct dentry *dentry;
+ struct kstat stat;
+ int deleted = 1;
+ int err;
+
+ if (!dev_mnt)
+ return 0;
+
+ nodename = device_get_nodename(dev, &tmp);
+ if (!nodename)
+ return -ENOMEM;
+
+ curr_cred = override_creds(&init_cred);
+ err = vfs_path_lookup(dev_mnt->mnt_root, dev_mnt,
+ nodename, LOOKUP_PARENT, &nd);
+ if (err)
+ goto out;
+
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
+ if (!IS_ERR(dentry)) {
+ if (dentry->d_inode) {
+ err = vfs_getattr(nd.path.mnt, dentry, &stat);
+ if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
+ err = vfs_unlink(nd.path.dentry->d_inode,
+ dentry);
+ if (!err || err == -ENOENT)
+ deleted = 1;
+ }
+ } else {
+ err = -ENOENT;
+ }
+ dput(dentry);
+ } else {
+ err = PTR_ERR(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+
+ path_put(&nd.path);
+ if (deleted && strchr(nodename, '/'))
+ delete_path(nodename);
+out:
+ kfree(tmp);
+ revert_creds(curr_cred);
+ return err;
+}
+
+/*
+ * If configured, or requested by the commandline, devtmpfs will be
+ * auto-mounted after the kernel mounted the root filesystem.
+ */
+int devtmpfs_mount(const char *mountpoint)
+{
+ struct path path;
+ int err;
+
+ if (!dev_mount)
+ return 0;
+
+ if (!dev_mnt)
+ return 0;
+
+ err = kern_path(mountpoint, LOOKUP_FOLLOW, &path);
+ if (err)
+ return err;
+ err = do_add_mount(dev_mnt, &path, 0, NULL);
+ if (err)
+ printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
+ else
+ printk(KERN_INFO "devtmpfs: mounted\n");
+ path_put(&path);
+ return err;
+}
+
+/*
+ * Create devtmpfs instance, driver-core devices will add their device
+ * nodes here.
+ */
+int __init devtmpfs_init(void)
+{
+ int err;
+ struct vfsmount *mnt;
+
+ err = register_filesystem(&dev_fs_type);
+ if (err) {
+ printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
+ "type %i\n", err);
+ return err;
+ }
+
+ mnt = kern_mount(&dev_fs_type);
+ if (IS_ERR(mnt)) {
+ err = PTR_ERR(mnt);
+ printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
+ unregister_filesystem(&dev_fs_type);
+ return err;
+ }
+ dev_mnt = mnt;
+
+ printk(KERN_INFO "devtmpfs: initialized\n");
+ return 0;
+}
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff